The year is 2301, man has ventured out into space and terraformed Mars into a planet of water, renamed it Aqua, and built an exact replica of old Venice by the name of Neo-Venezia.
Akari Mizunashi comes to Neo-Venezia from Earth (Now known as Man-Home) to become a gondolier trainee at Aria Company. Through difficult training Akari is going to become a Prima, and during her training she encounters many mysterious events.